feat: EntityLoader 구현

src/main/java/persistence/entity/EntityLoader.java

@@ -0,0 +1,49 @@
+package persistence.entity;
+
+import jdbc.RowMapper;
+import jdbc.exception.RowMapException;
+import persistence.sql.util.ColumnFields;
+import persistence.sql.util.ColumnName;
+
+import java.lang.reflect.Field;
+import java.sql.ResultSet;
+import java.sql.ResultSetMetaData;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+public class EntityLoader<T> implements RowMapper<T> {
+ private final Class<T> clazz;
+ private final Map<String, Field> fieldsByName;
+
+ public EntityLoader(Class<T> clazz) {
+ this.clazz = clazz;
+ this.fieldsByName = ColumnFields.forQuery(clazz)
+ .stream().collect(Collectors.toMap(
+ ColumnName::build,
+ field -> {
+ field.setAccessible(true);
+ return field;
+ }
+ ));
+ }
+
+ @Override
+ public T mapRow(ResultSet resultSet) {
+ try {
+ final T object = clazz.getDeclaredConstructor().newInstance();
+ final ResultSetMetaData metaData = resultSet.getMetaData();
+ final int columnCount = metaData.getColumnCount();
+ for (int i = 1; i <= columnCount; i++) {
+ fieldsByName.get(
+ metaData.getColumnLabel(i)
+ ).set(
+ object,
+ resultSet.getObject(metaData.getColumnName(i))
+ );
+ }
+ return object;
+ } catch (Exception e) {
+ throw new RowMapException(e);
+ }
+ }
+}

src/main/java/persistence/entity/EntityManagerImpl.java

@@ -1,7 +1,6 @@
 package persistence.entity;
 
 import jdbc.JdbcTemplate;
-import jdbc.RowMapperImpl;
 import persistence.sql.dml.DmlBuilder;
 
 import java.util.List;
@@ -80,7 +79,7 @@ private <T> Optional<T> findFromDB(EntityKey<T> key) {
  Class<T> clazz = key.getEntityClass();
  List<T> entities = jdbcTemplate.query(
  dml.getFindByIdQuery(clazz, key.getEntityId()),
- new RowMapperImpl<>(clazz)
+ new EntityLoader<>(clazz)
  );
  if (entities.isEmpty()) {
  return Optional.empty();